Exhaust gas aftertreatment systems for internal combustion engines may typically include one or more aftertreatment components configured to process the exhaust gas in a manner that removes one or more undesirable constituents from the exhaust gas. It is desirable to monitor the operation of one or more such aftertreatment components to diagnose degradation in the ability of the one or more aftertreatment components to remove the one or more undesirable constituents from the exhaust gas.